C3 to C5 polyfluoroalkanes propellants

ABSTRACT

Polyfluoroalkanes are used as propellants in sprayable compositions or in the the preparation of plastic foams and in the electrical industry as cleansing and degreasing agents.

This is a division of application Ser. No. 07/469,622, filed Jan. 24,1990 now pending.

The present invention relates to the use of C₃ to C₅ polyfluoroalkanescomprising at least two fluorine atoms as propellants, especially foraerosols and in the production of plastic foams.

The use of fluorochlorohydrocarbons, for example trichlorofluoromethane,dichlorodifluoromethane and trichlorofluoroethane, as propellants forthe above purposes, is known. According to more recent studies, thechlorine content of conventional propellants damages the ozone layer ofthe earth's atmosphere (see J. F. D. Mills, Cell. Polym. 5, 343 (1987)and F. S. Rowland et al., Nature 239, 8 (1974)); for this reason limitshave been specified for the amounts of fluorochorohydrocarbons produced.The need has therefore arisen for chlorine-free propellants.

We have now found that those polyfluoroalkanes of the formula

    CX.sub.3 --CY.sub.2 --R                                    (I),

wherein

the radicals X located on the same carbon atom stand for hydrogen and/orfluorine,

the radicals Y located on the same carbon atom stand for hydrogen,fluorine and/or CF₃, and

R stands for CH₂ F, CHF₂, CH₃, CF₃, CF₂ --CH₃, CF₂ CH₂ F, CH₂ --CH₃, CH₂--CH₂ --CH₃ or --CH(CH₃)--CH₃,

and wherein the polyfluoroalkanes of the formula (I) contain at leasttwo fluorine atoms, can be used advantageously as propellants.

Those polyfluoroalkanes of the formula (I) are preferred which contain 3to 7, particularly 4 to 6 fluorine atoms.

Furthermore, those polyfluoroalkanes of the formula (I) are preferred inwhich the CX₃ group represents a CF₃, CHF₂ or CH₃ group and the CY₂group represents a CH₂, CHF, CF₂ or C(CF₃)H group.

For the use according to the invention, those individual compoundsconforming to formula (I) in which X₃, Y₂ and R are present in one ofthe combinations listed in Table 1, are particularly preferred.

                  TABLE 1    ______________________________________    X.sub.3      Y.sub.2    R    ______________________________________    F.sub.3      H.sub.2    CH.sub.2 F    F.sub.3      HF         CH.sub.2 F    F.sub.3      H.sub.2    CHF.sub.2    HF.sub.2     F.sub.2    CH.sub.2 F    F.sub.3      HF         CH.sub.3    H.sub.3      F.sub.2    CH.sub.3    F.sub.3      F.sub.2    CF.sub.2 --CH.sub.3    F.sub.3      HF         CF.sub.2 --CH.sub.3    F.sub.3      H.sub.2    CF.sub.2 --CFH.sub.2    F.sub.3      H.sub.2    CH.sub.2 --CH.sub.3    H.sub.3      F.sub.2    CF.sub.2 --CH.sub.3    F.sub.3      H.sub.2    CF.sub.2 --CH.sub.3    F.sub.3      HCF.sub.3  CH.sub.3    F.sub.3      H.sub.2    CH.sub.2 --CH.sub.2 --CH.sub.3    F.sub.3      H.sub.2    --CH(CH.sub.3)--CH.sub.3    F.sub.3      H.sub.2    CF.sub.3    ______________________________________

The methods for preparing the polyfluoroalkanes for use according to theinvention are known (see, for example, Zh. Org. Khim. 1980, 1401-1408and 1982, 946 and 1168; Zh. Org. Khim. 1988, 1558; J. Chem. Soc. Perk.1, 1980, 2258; J. Chem. Soc. Perk. Trans. 2, 1983, 1713; J. Chain. Soc.C 1969, 1739; Chem. Soc. 1949, 2860; Zh. Anal. Khim. 1981 36 (6), 1125;J. Fluorine Chem. 1979, 325; Izv. Akad. Nauk. SSSR, Ser. Khim. 1980,2117 (in Russian); Rosz. Chem. 1974 (48), 1697 and J.A.C.S. 67, 1195(1945), 72, 3577 (1950) and 76, 2343 (1954)).

The propellants for use according to the invention are particularlysuitable for aerosols and production of plastic foams; the individualcompounds of the formula (I), mixtures of compounds of the formula (I)and mixtures of compounds of the formula (I) with conventionalpropellants may be used for this purpose. Individual compounds of theformula (I) or mixtures of compounds of the formula (I) are preferred.

Suitable aerosols are those employed for cosmetic and medicinalpurposes, for example deodorant aerosols, anti-asthma sprays and liquidplaster sprays. Aerosols which employ the propellants for use accordingto the invention, are distinguished by the fact that the propellant isinert and the ozone layer of the earth's atmosphere is no longernegatively affected by the corresponding amount of propellants accordingto the invention, since they are chlorine-free.

The methods of producing plastic foams using propellants is generallyknown. In the production of closed-cell foams the propellants may alsoact as heat-insulating cellular gases. This is also true for thepropellants for use according to the invention.

The propellants for use according to the invention may be employed, forexample, in the production of foams based on isocyanates, polystyrenes,polyvinyl chlorides and phenol-formaldehyde condensates. They arepreferably used in the production of foams based on isocyanates, inparticular in the production of polyurethane and/or polyisocyanuratefoams; they are especially preferred in the production of rigid foamsbased on isocyanates.

The production of foams based on isocyanates is known per se and isdescribed, for example, in German Offenlegungsschriften 1,694,142,1,694,215 and 1,720,768, as well as in Kunststoff-Handbuch [PlasticsHandbook], volume VII, Polyurethane, edited by Vieweg and Ho/ chtlen,Carl Hanser Verlag, Munich 1966, and in the new edition of this tome,edited by G. Oertel, Carl Hanser Verlag, Munich, Vienna, 1983.

These foams are mainly those comprising urethane and/or isocyanurateand/or allophanate and/or uretdione and/or urea and/or carbodiimidegroups.

The following can be employed for the production of foams based onisocyanates, using propellants according to the invention:

a) As starting components aliphatic, cycloaliphatic, araliphatic,aromatic and heterocyclic polyisocyanates, such as those described, forexample, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pp.75-136, for example those of the formula

    Q(NCO).sub.n

in which

n denotes 2-4, preferably 2-3, and

Q denotes an aliphatic hydrocarbon radical of 2-18, preferably 6-10carbon atoms, a cycloaliphatic hydrocarbon radical of 4-15, preferably5-10 carbon atoms, an aromatic hydrocarbon radical of 6-15, preferably6-13 carbon atoms or an araliphatic hydrocarbon radical of 8-15,preferably 8-13 carbon atoms, for example such polyisocyanates asdescribed in DE-OS 2,832,253, pp. 10-11. Particularly preferred areusually those polyisocyanates which are technically readily accessible,for example the 2,4- and 2,6-toluylene diisocyanate as well as anymixture of these isomers ("TDI");polyphenylpolymethylenepolyisocyanates, such as those obtained by ananiline-formaldehyde condensation and subsequent treatment with phosgene("crude MDI"), and polyisocyanates comprising carbodiimide groups,urethane groups, allophanate groups, isocyanurate groups, urea groups orbiuret groups ("modified polyisocyanates"), especially those modifiedpolyisocyanates which are derived from 2,4- and/or 2,6-toluylenediisocyanate and from 4,4'- and/or 2,4'-diphenylmethane diisocyanate.

b) The starting components may further be compounds of a molecularweight usually of 400 to 10,000, containing at least two hydrogen atomsreactive toward isocyanates. These comprise, besides compoundscontaining amino, thio or carboxyl groups, preferably compoundscontaining hydroxyl groups, in particular compounds containing 2 to 8hydroxyl groups, especially those of a molecular weight of 1,000 to6,000, preferably 2,000 to 6,000, for example polyethers and polyestersas well as polycarbonates and polyester amides containing at least 2,usually 2 to 8, preferably 2 to 6 hydroxyl groups; these compounds areknown per se for the preparation of homogeneous and cellularpolyurethanes and are disclosed, for example, in DE-OS 2,832,253, pp.11-18.

c) When appropriate, compounds comprising at least two hydrogen atomsreactive toward isocyanates and of a molecular weight of 32 to 399 maybe used as further starting components. Also in this case compoundscontaining hydroxyl groups and/or amino groups and/or thiol groupsand/or carboxyl groups, preferably compounds containing hydroxyl groupsand/or amino groups, are understood to be those which are used as chainlengtheners or crosslinking agents. These compounds usually have 2 to 8,preferably 2 to 4 hydrogen atoms reactive toward isocyanates.Appropriate examples are disclosed in DE-OS 2,832,253, pp. 19-20.

d) One polyfluoroalkane or several polyfluoroalkanes of the formula (I)as propellant and insulating gas, if appropriate in admixture withconventional propellants and insulating gases.

e) When appropriate, other auxiliary agents and additives may be used atthe same time, such as

water and/or other highly volatile organic substances as propellants,

additional catalysts of the type known per se in amounts up to 10% byweight, based on the component b),

surface-active additives, such as emulsifiers and foam stabilizers,

reaction retardants, for example acidic substances such as hydrochloricacid or organic acid halides, also cell regulators of the type known perse such as paraffins or fatty alcohols or dimethylpolysiloxanes as wellas pigments or dyes and other flame retardants of the type known per se,for example tricresyl phosphate, also stabilizers against the effects ofageing and weathering, plasticizers and fungistats and bacteriostats aswell as fillers such as barium sulphate, kieselguhr, carbon black orwhiting.

Other examples of surface active additives, foam stabilizers, cellregulators, reaction retardants, stabilizers, flame retardants,plasticizers, dyes, fillers, fungistats, bacteriostats to be used at thesame time if appropriate, as well as details concerning the use andaction of these additives are described in Kunststoff-Handbuch [PlasticsHandbook], volume VII, edited by Vieweg and Ho/ chtlen, Carl HanserVerlag, Munich 1966, for example on pages 103-113.

The isocyanate-based foams can be prepared in a manner known per se.

The preparation of polyurethane plastics may be prepared, for example,as follows: the reactants are caused to react by the single-stageprocess known per se, the prepolymer process or the semiprepolymerprocess, frequent use being made of plant machinery, for example thatdisclosed in U.S. Pat. No. 2,764,565. Details concerning the processingplant which are likewise relevant according to the invention, aredescribed in Kunststoff-Handbuch, volume VII, edited by Vieweg and Ho/chtlen, Carl Hanser Verlag, Munich 1966, for example on pages 121 to205.

According to the invention it is also possible to produce cold-curingfoams (cf. GB-PS 1,162,517, DE-OS 2,153,086).

Foams may of course also be produced by block foaming or by the doubleconveyor belt process known per se.

The products obtainable according to the invention may be used, forexample, as insulation panels for roof insulation.

In foam production, the propellants for use according to the inventionmay be employed, for example, in amounts of 1 to 30% by weight,preferably 2 to 10% by weight, in each case based on the foam.

Compared with conventional foams of similar or virtually identical cellstructure, foams produced by propellants for use according to theinvention are distinguished by the fact that in their production,application and disposal they no longer negatively affect the ozonelayer of the earth's atmosphere by the corresponding amount of thepropellants according to the invention.

Polyfluoroalkanes of the formula (I) may be further employed asdegreasing and cleansing agents in the electrical industry. The samepolyfluoroalkanes are preferred for this purpose as those referred toabove as being preferred. Here, too, the individual compounds of theformula (I), mixtures of compounds of the formula (I) and mixtures ofcompounds of the formula (I) with conventional degreasing and cleansingagents may be employed.

EXAMPLE 1

100 g of a polyether with a hydroxyl value of 380, which has resultedfrom the addition of propylene oxide to a solution of saccharose,propylene glycol and water,

2 g of a siloxane polyether copolymer as foam stabilizer,

3.8 g of water and

3 g of dimethylcyclohexylamine were mixed.

100 g of this mixture were thoroughly mixed with

15 g of 1,1,1,3,3,3-hexafluoro-2-methylpropane as propellant, using alaboratory stirrer.

This mixture was foamed with 152 g of crude4,4'-diisocyanatodiphenylmethane. A rigid polyurethane foam wasobtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 10    Setting time     (s)          : 42    Free density     (kg/m.sup.3) : 24    Cell structure                : fine    ______________________________________

EXAMPLE 2

100 g of a polyether with a hydroxyl value of 380 which results from theaddition of propylene oxide to a solution of saccharose, propyleneglycol and water,

2 g of a siloxane polyether copolymer as foam stabilizer,

3.8 g of water and

3 g of dimethylcyclohexylamine were mixed.

100 g of this mixture were thoroughly mixed with

15 g of 1,1,1,3,3,3-hexafluoropropane as propellant, using a laboratorystirrer.

This mixture was foamed with 152 g of crude4,4'-diisocyanatodiphenylmethane. A rigid polyurethane foam wasobtained. Foam and physical data:

    ______________________________________    Induction time   (s)          : 10    Setting time     (s)          : 40    Free density     (kg/m.sup.3) : 22    Cell structure                : fine.    ______________________________________

EXAMPLE 3

100 g of a polyether with a hydroxyl value of 380 which results from theaddition of propylene oxide to a solution of saccharose, propyleneglycol and water,

2 g of a siloxane polyether copolymer as foam stabilizer,

3.8 g of water and

3 g of dimethylcyclohexylamine were mixed.

100 g of this mixture were thoroughly mixed with 15 g of2,2,4,4-tetrafluorobutane as propellant, using a laboratory stirrer.

This mixture was foamed with 152 g of crude4,4'-diisocyanatodiphenylmethane. A rigid polyurethane foam wasobtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 10    Setting time     (s)          : 39    Free density     (kg/m.sup.3) : 21    Cell structure                : fine.    ______________________________________

EXAMPLE 4

60 g of a polyether with a hydroxyl value of 950 which resulted from theaddition of propylene oxide to trimethylpropane,

40 g of a polyether with a hydroxyl value of 56 which resulted from theaddition of propylene oxide to trimethylpropane,

0.5 g of water and

2 g of a siloxane polyether copolymer as foam stabilizer were mixed.

100 g of this mixture was thoroughly mixed with 10 g of1,1,1,3,3,3-hexafluoro-2-methylpropane as propellant, using a laboratorystirrer.

This mixture was foamed with 164 g of crude4,4'-diisocyanatodiphenylmethane. A rigid solid polyurethane plastic wasobtained. Foaming and physical data:

    ______________________________________    Induction time     (s)        : 75    Setting time       (s)        : 120    Free density       (kg/m.sup.3)                                  : 75    Total density compacted                       (kg/m.sup.3)                                  : 350    Cell structure                : fine.    ______________________________________

EXAMPLE 5

60 g of a polyether with a hydroxyl value of 950 which resulted from theaddition of propylene oxide to trimethylpropane,

40 g of a polyether with a hydroxyl value of 56, which resulted from theaddition of propylene oxide to trimethylolpropane,

0.5 g of water and

2 g of a siloxane polyether copolymer as foam stabilizer were mixed.

100 g of this mixture were thoroughly mixed with

10 g of the 1,1,1,3,3,3-hexafluoropropane according to the invention aspropellant, using a laboratory stirrer.

This mixture was foamed with 164 g of crude4,4'-diisocyanatodiphenylmethane. A rigid solid polyurethane plastic wasobtained. Foaming and physical data:

    ______________________________________    Induction time     (s)        : 88    Setting time       (s)        : 136    Free density       (kg/m.sup.3)                                  : 70    Total density compacted                       (kg/m.sup.3)                                  : 350    Cell structure                : fine.    ______________________________________

EXAMPLE 6

60 g of a polyether with a hydroxyl value of 950 which resulted from theaddition of propylene oxide to trimethylolpropane,

40 g of a polyether with a hydroxyl value of 56 which resulted from theaddition of propylene oxide to trimethylolpropane,

0.5 g of water and

2 g of a siloxane polyether copolymer as foam stabilizer were mixed.

100 g of this mixture were thoroughly mixed with

10 g of 2,2,4,4-tetrafluorobutane as propellant, using a laboratorystirrer.

This mixture was foamed with 164 g of crude4,4'-diisocyanatodiphenylmethane. A rigid solid polyurethane plastic wasobtained. Foaming and physical data:

    ______________________________________    Induction time     (s)        : 83    Setting time       (s)        : 138    Free density       (kg/m.sup.3)                                  : 68    Total density compacted                       (kg/m.sup.3)                                  : 350    Cell structure                : fine.    ______________________________________

EXAMPLE 7

91 g of a polyether with a hydroxyl value of 56 which resulted from theaddition of propylene oxide to trimethylolpropane,

9 g of monoethylene glycol and

0.1 g of water were mixed.

100 g of this mixture were thoroughly mixed with 15 g of1,1,1,3,3,3-hexafluoro-2-methylpropane as propellant, using a laboratorystirrer.

This mixture was foamed with 56 g of crude4,4'-diisocyanatodiphenylmethane. A tough and resilient polyurethanefoam was obtained. Foaming and physical data:

    ______________________________________    Induction time     (s)        : 33    Setting time       (s)        : 112    Free density       (kg/m.sup.3)                                  : 131    Total density compacted                       (kg/m.sup.3)                                  : 350    Cell structure                : fine.    ______________________________________

EXAMPLE 8

91 g of a polyether with a hydroxyl value of 56, which resulted from theaddition of propylene oxide to trimethylolpropane,

9 g of monoethylene glycol and

0.1 g of water were mixed.

100 g of this mixture were thoroughly mixed with 15 g of1,1,1,3,3,3-hexafluoropropane as propellant, using a laboratory stirrer.

This mixture was foamed with 56 g of crude4,4'-diisocyanatodiphenylmethane. A tough and resilient polyurethanefoam was obtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 36    Setting time     (s)          : 108    Free density     (kg/m.sup.3) : 121    Cell structure                : fine.    ______________________________________

EXAMPLE 9

91 g of a polyether with a hydroxyl value of 56, which resulted from theaddition of propylene oxide to trimethylolpropane,

9 g of monoethylene glycol and

0.1 g of water were mixed.

100 g of this mixture were thoroughly mixed with

15 g of 2,2,4,4-tetrafluorobutane as propellant, using a laboratorystirrer.

This mixture was foamed with 56 g of crude4,4'-diisocyanatodiphenylmethane. A tough and resilient polyurethanefoam was obtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 38    Setting time     (s)          : 108    Free density     (kg/m.sup.3) : 117    Cell structure                : fine    ______________________________________

EXAMPLE 10

100 g of a polyether with a hydroxyl value of 56, which resulted fromthe addition of propylene oxide to trimethylolpropane,

3 g of water,

1 g of a siloxane polyether copolymer as foam stabilizer,

0.05 g of dibutyltin dilaurate were mixed.

100 g of this mixture were thoroughly mixed with 10 g of1,1,1,3,3,3-hexafluoro-2-methylpropane as propellant, using a laboratorystirrer.

This mixture was foamed with 41 g of toluylene diisocyanate. A flexiblepolyurethane foam was obtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 8    Setting time     (s)          : 105    Free density     (kg/m.sup.3) : 28    Cell structure                : fine.    ______________________________________

EXAMPLE 11

100 g of a polyether with a hydroxyl value of 56, which resulted fromthe addition of propylene oxide to trimethylolpropane,

3 g of water,

1 g of a siloxane polyether copolymer as foam stabilizer,

0.05 g of dibutyltin dilaurate were mixed.

100 g of this mixture were thoroughly mixed with 10 g of1,1,1,3,3,3-hexafluoropropane as propellant, using a laboratory stirrer.

This mixture was foamed with 41 g of toluylene diisocyanate. A flexiblepolyurethane foam was obtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 8    Setting time     (s)          : 103    Free density     (kg/m.sup.3) : 26    Cell structure                : fine.    ______________________________________

EXAMPLE 12

100 g of a polyether with a hydroxyl value of 56, which resulted fromthe addition of propylene oxide to trimethylolpropane,

3 g of water,

1 g of a siloxane polyether copolymer as foam stabilizer,

0.05 g of dibutyltin dilaurate were mixed.

100 g of this mixture were thoroughly mixed with 10 g of2,2,4,4-tetrafluorobutane as propellant, using a laboratory stirrer.

This mixture was foamed with 41 g of toluylene diisocyanate. A flexiblepolyurethane foam was obtained. Foaming and physical data:

    ______________________________________    Induction time   (s)          : 8    Setting time     (s)          : 108    Free density     (kg/m.sup.3) : 25    Cell structure                : fine.    ______________________________________

What is claimed is:
 1. A process for producing a polyisocyanate-derivedfoam by reacting the components comprising a polyisocyanate and acompound having at least two hydrogen atoms reactive toward isocyanategroups, the reaction between said components being accompanied by ablowing step, which comprises carrying out the blowing step with the aidof a blowing agent comprising from 1 to 30% by weight of the foam of analiphatic fluoroalkane of the formula

    C.sub.4 H.sub.2 F.sub.8.


2. A process for producing a polyisocyanate-derived foam by reacting thecomponents comprising a polyisocyanate and a compound having at leasttwo hydrogen atoms reactive toward isocyanate groups, the reactionbetween said components being accompanied by a blowing step, whichcomprises carrying out the blowing step with the aid of a blowing agentcomprising from 1 to 30% by weight of the foam of one or more aliphaticfluoroalkanes of the formula

    C.sub.4-5 H.sub.1-4 F.sub.8-9.